<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<form action="">
    用户名<input type="text" name="username">
    密码<input type="password" name="password">
    <input type="hidden" th:value="${redirect_url}" name="redirect_url">
    <input type="submit" value="点击登录">
</form>